Blair said he planned to move the May 29 election for Northern Ireland's dissolved legislature to the autumn. But he warned the vote could be delayed longer if the outlawed Irish Republican Army doesn't explicitly renounce violence, cease all hostile activities and disarm.

Gaining such an IRA commitment "goes to the very soul of the Good Friday agreement," he said, referring to the 1998 pact that proposed power-sharing between British Protestants and Irish Catholics in the province. He accused the IRA's Sinn Fein party of a "point-blank refusal" to go beyond "general assurances" on future IRA actions.

Northern Ireland legislators in 1999 overcame deep Protestant divisions to form a four-party administration that included Sinn Fein.

But Britain, fearing a walkout by the main Protestant party, shut down the crisis-prone coalition last October after police implicated Sinn Fein in an alleged IRA spy ring. It was the latest in a string of scandals that raised questions about the sincerity of the IRA's 1997 cease-fire.

Blair said that without decisive IRA peace moves to reassure Protestant voters, a majority would probably back Ian Paisley's hard-line Democratic Unionist Party, which opposed the peace deal.

A Paisley victory, Blair said, would be "a recipe for complete and total chaos. So the reality is, I'm afraid, unless we get an agreement (with Sinn Fein and the IRA), we don't have a government."

The traditional No. 1 Protestant party, the Ulster Unionists, welcomed the postponement, as did the Bush administration.

"We believe Sinn Fein must provide a clear and unequivocal commitment that all paramilitary activities will be terminated ... including the decommissioning of all of its arms on terms that will enhance confidence," said State Department spokesman Philip Reeker.

But the other three parties in the mothballed coalition -- Sinn Fein, the Democratic Unionists and the moderate Catholics of the Social Democratic and Labor Party -- denounced the move.

Irish Prime Minister Bertie Ahern, who has worked with Blair for six months to try to achieve an IRA breakthrough, had agreed with Blair in March to postpone the election from May 1 to May 29. But he criticized Thursday's move.

"Ultimately, I believe that yet another postponement causes more problems for the process than it solves," Ahern said.

He did agree that the IRA's seven-man command -- among them, according to police and historians, Sinn Fein leaders Gerry Adams and Martin McGuinness -- had the power to defuse the crisis.

"I regret that we did not have a clear and unambiguous IRA statement to begin with. This would have solved everything," Ahern said.

In a bid to maintain peacemaking momentum, Blair and Ahern made public Thursday their governments' long-awaited plans for driving forward key goals of the 1998 deal.

The 25-page joint declaration -- dramatically withdrawn from publication on the fifth anniversary of the Good Friday deal April 10 -- had already been presented confidentially to Sinn Fein in the hope of spurring a maximum IRA response.

Britain pledged to reduce troop strength in Northern Ireland, currently around 13,000, to a "permanent garrison" of about 5,000 by April 2005. All but 14 army bases in the territory would be closed by then if the IRA provided "an enabling environment," the document said.

The two governments also pledged to appoint four experts -- one British, one Northern Irish, one Irish and one American -- to monitor the IRA and other outlawed groups, as well as Britain's pursuit of security reforms and cutbacks.

Britain also promised that about 30 fugitives wanted on outstanding IRA charges "would be free to return to Northern Ireland without risk of arrest for questioning or charge."

More than 500 IRA prisoners and Protestant extremists have already won early paroles under terms of the 1998 deal, but fugitives had not been covered.

McGuinness welcomed the British-Irish document's publication, but insisted the IRA had made sincere peace commitments. The senior Sinn Fein negotiator called on Catholics to mount mass protests May 29.

He accused Ulster Unionist Party leader David Trimble of seeking "to humiliate the IRA" and "constantly looking over his shoulder at the Rev. Ian Paisley and to opposition within his own party."